Hydraulic control mechanism



Aug- 6, 1940. P. N, ossRl-lourzsieY 2,210,427`

HYDRAULIC CONTROL MEcHANIsu Filed Dec. 7. 1938 2 Sheets-Sheet l P.N.YoBER`HoL'rzER H'YDRAULIG CONTROLMECHANISM Filed Dec. 7, 1958 mlnPanarea Aug. s, 1940 UNITED LsltaTlzs HYDRAULIC CONTROL IVIECHANISM PaulN. Oberholtzer, Philadelphia., Pa., assignorv to American EngineeringCompany, Philadelphia, Pa., Aa corporation of Pennsylvania ApplicationvDecember 7, 1938, Serial No. 244,343

3 Claims.

This invention relates to hydraulic control devices, and moreparticularly to devices for controlling the pressures developed bypumps.

One object of the present invention is 'to pro- 5 vide in a fluid systemincluding a variable stroke pump, control means which enables operationof the pump at any one of a number of predetermined-pressures.

A further object is to provide in a fluid system l of the statedcharacteradjustable means for conditioning a pump for operation at anyonev of a wide range of pressures, and additional means operable uponsaid pump wherebythe pressures developed thereby may be changed at willand l maintained constant for any desired period of time.

Other and further objects will become apparent as the description of theinvention progresses.

0f the drawings:

Fig. 1 is a general assembly view. diagrammatic in part, of the fluidcontrol device comprising the present invention, several of the elementsthereof being shown in section.

Fig. 2 is a side elevational view partly in sectionof the pump'and thecontrol means theredesignates generally the fluid system, which in thepresent instance comprises a pump .2, a hydraulic p ress 3, presscontrol valve 4, pump control valves 5 and 6, and fluid motors 1, 8 and9.

Pump 2 may be vof the radialpiston type shown and described in PatentNo. 1,077,979, andmay be'operated by an electric motor III, or by anyother suitable power means. Pump 2 and motor Ill are suitably mountedupon a supply tank Il, .from which 'fluid is drawn into the pump 2through a pipe I2. The fluid so drawn into pump 2 is dischargedtherefrom through a pipe I3. Pipe I3 is connected at one end thereof tothe inlet port |4 of press control valve 4. Valve 4 comprises a casingI5, rhaving a cylindrical chamber I6 provided therein, which at alltimes -is in communication with inlet port I4. Chamber. I6 alsocommunicates with a pair of spaced ports Il and I8 to which arerespectively connected one end of a pair of pipes I9 and v2|).

'I'he other ends of pipes I9 and 20 are connected to the lower and upperends respectively, of the cylinder 2| of a fluid motor.22 secured in anysuitable manner to the frame 23 of hydraulic press 3. The opposite endsof chamber |6 are connected by a passage 24 provided in casing I5, 5which in turn communicates with a discharge port 25. Discharge port 25is connected to supy ply tank II by means of a pipe 26. Operating v inchamber I6 of valve 4 is a valve element 21 comprising a pair of spaced,interconnected valve l0 heads 28 and 29. A valve stem 30 is connected tovalve head 29 and extends through the lower end of casing I5. The freeend of valve stem 30 is pivotally connected to a lever 3| intermediatethe'ends of the latter. one end thereof to the lower end of a link 32,the other end of said link being pivotally mounted on an4 ear 33,secured to and extending laterally from the lower end of casing I5. Whenlever 3| is in the full line position shown in Fig. 1, 20 the uid frompump" 2 ows to the lower end of cylinder 2| through pipe I3, port |4 ofvalve 4, chamber I6, port and pipe I9. 'I'he piston 34 operating incylinder 2| is therefore moved upwardly.A The fluid at the upper end ofcylinder 25 2| now discharges to exhaust through pipe 20, port I8, thelower end of chamber Iii, passage 24, and pipe 26. When lever 30 ismoved to the dotted line position shown in Fig. 1, the fuid enteringchamber I6 of valve 4 flows through 30 port I8 land is conducted to theupper end of cylinder 2| by pipe 20, thereby causing thepiston 34 todescend. The fluid at the lower endof cylinder 2| now flows to supplytank II through pipe I9,.port I'l, the upper end of chamber I6, 35passage 24 and pipe 26. Piston 34 has'secured thereto a piston rod 35,to the upper end 'of which is secured a platen 36. Consequently whenpiston 34 is moved upwardly platen 36 is actuated toward the work whichmay be attached 40 to the head 31 of press 3. The head 31, as shown inFig. 1, is secured to the upper end of the frame 23 and extendslaterally therefrom.

'I'he present'invention contemplates control means which enablesoperation of the device at 45 any one of a number of pressures. Themeans for accomplishing these results will now be described in detail. v

Referring more particularly to Fig. 2, it will be observed thata bracket4| is secured t0 the 50 left hand side of pump 2 by any suitable means,such as by bolts 42. The upper end of brackety 4| has provided thereinthe cylinder 43 of fluid motor 8. Secured to the opposite side of pump 2by bolts 44 is a second bracket 45. The lower 65 Lever 3| is pivoted at15 end of this bracket has formed therein the cylinder 46 of the 'fiuidmotor 1. The vertical extension 41 of bracket 45 has provided therein ahorizontally disposed aperture 48 through which extends a rod 49. Theleft hand end of rod 49 extends through the central bore 50 of a nut 5|which makes threaded engagement with the enlarged portion 52 of cylinder43. Rod 49 has slidably mounted thereon a crosshead 53 against which oneend of a coil spring 54 abuts. Spaced from crosshead 53 and secured torod 49 by any suitable means, such as a screw 55', is an adjustablespring seat 55 against which the other end of spring 54 abuts. Crosshead53 has provided at the opposite ends thereof a pair of rectangular guideblocks 56 and 51, which respectively receive the upper bifurcated ends58 and 59 of a pair of levers 60 and 8|. Levers 60 and 6I are pivotedintermediate their ends on a rod 62, mounted in any suitable manner inbracket 45. The lower bifurcated ends 63 and 64 of lever 60 and 6|engage a pair of substantially rectangular bearing blocks 65 and 66pivotally mounted on guide rods 61 and 68, respectively. l The left handends of guide rods 61 and 68` are Isecured to the sliding blocks 69 o`fpump 2,

vwhile the right hand ends thereof are secured in any suitable mannerVto a crosshead 10, such as by nuts 1|, engaging the outer threaded endsof said guide rods. Cylinder 46 of iiuid motor 1 has operating therein apiston 12, the right hand end (Fig. 2) of which engages the inner sideof crosshead 10, at a point substantially midway between guide rods 61and 68. 'I'he left hand end of cylinder 46 communicates with asubstantially vertical port 13 provided in the lower end of bracket 45,and to which one end of a pipe 14 is connected. The other end of pipe 14is connected topipe |3 by means of a T coupling 15, and a short pipe 16.

The portion of rod 49 extending beyond the `right hand side of bracket45 is provided with screw threads 11, for receiving a` pair ofcorrespondingly threaded nuts 18. It therefore is apparent that toadjust the tension of spring 54 it is only necessary to adjust the nuts18, which causes an axial movement of rod 49.l After proper adjustmentof spring 54, the nuts 18 may be held against accidental movement by aset screw 18', or by any other suitable means. If the nuts 18 are soadjusted as to cause rod 49 to move to the right, spring seat 55 willtend to compress spring 54. The pressure thus created in-.lspring 54tends to slide crosshead 53 to the right, which in turn swings levers 60and 6| in a clockwise direction about their pivot 62. This action oflevers 60 and 6| causes the sliding blocks 69 of pump 2 to move to theleft by virtue of the connection thereof with guidefrods 61 and 68.

The sliding. blocks 69 of'pump 2 will' remain inadjusted position untilthe pressure imposed upon the left hand end of piston 12 exceeds thepressure of spring 54. When this occurs piston 12 will move to theright, thereby actuating crosshead 10, guide rods 61 and 88, andconsequently the sliding blocks -69 to leakage stroke position.v

The cylinder 43 of fluid' motor 8 also has operating therein a piston8|. The right hand end of piston 8| extends into the enlarged bore 82 atthe left hand end (Fig. 2), of nut 5| ,p and is adapted to engage theleft hand end of rod 49. It will be noted that the diameter of piston 8|is greater than that of rod 49, and that the movement of piston 8| tothe right is limited by the annular-shoulder 83 at the right band end ofcrosshead |20 intermediate the ends of the latter.

of a series of connections which will now be described in detail.

Cylinder 43 of motor 8 has secured to the left hand end thereof a plug84 having a central port 85 provided therein. .The outer end of port 25is connected to the port 86 of valve 5 by a pipe 81.

. Valve 5 is provided to control the operation of fluid-motor 8, andcomprises a casing 88 having a cylindrical chamber 89 provided centrallythereof. Operating in chamber 89 is a valve element 90 comprising a pairof spaced interconnected valve heads 9| and 92. A stem 93 is connectedto valve element 90, and extends through an aperture provided in the endwall of casing 88. The free end of valve stem 93 is pivotally connectedto a lever 94 intermediate the ends of the latter. Lever 94 is pivotallyconnected to the upper end of a link 95, pivoted at the lower endthereof to a laterally extending ear 96 secured to casing 88. The casing88 'of valve 5 has also provided therein ports 91 and 98, the former ofwhich has connected thereto one end of a pipe 99, the other end of whichbeing connected to a pipe |88, which in turn is connected to makeup tankPort 98 is connected to a port |0| of valve 6, by means of apipe |02,the pipe |02 being connected intermediate the ends thereof to a branchpipe |03, which in turn is connected to the pressure pipe I3 leadingfrom pump 2.

Valve 6 is provided to control the operation of iluid motor 9 and issimilar in construction to valve 5, it also comprising a casing |04having a cylindrical chamber |05 provided centrally thereof. Operatingin chamber |05 is a valve element |08 comprising a pair of spaced valveheads I 01 and |08. A stem |09 is connected to valve element |05 andextends through an aperture provided at the upper end of casing |04 andis pivotally attached to a lever 4| |0 intemediate the ends thereof. Theleft hand end of lever ||0 is pivoted to the upper end of a link pivotedat the lower end thereof to a laterally extending ear ||2 secured tocasing |04. Valve casing |04 has also provided therein ports ||3 and||4, the former of which is connected to the port |23 (Fig. 2) of motor9 by a pipe I5, while the latter is connected to pipe |00. n

Referring to Fig. 2, it will be observed that the motor 9 comprises acylinder ||1 formed at the lower endof bracket 4|, in which operates apiston ||8. The right hand end (Fig. 2) of piston ||8 extends through agland ||9 and engages a.

Crosshead |20 has secured to the opposite ends thereof a pair of guiderods |2| which extend through suitable aperturesy provided in the lefthand side of the casing of pump 2 and are secured in any suitable mannerto sliding blocks 69 lof said pump.

To prevent movement of brackets 4| and 46 away from eachother under thehigher pressure conditions of the system, a tie rod |24 is provided.This tie rod extends through apertures provided in the upper ends ofbrackets 4| and 45 and is secured thereto by nuts |25, as shown in Figs.l and 2. It will also be observed that any leakage of fluid past Vpiston8| of motor 8 drains to supply tank through a pipe |26.

From the foregoing description it -is thought that the operation of 'myimproved hydraulic control device is apparent. However, to correlate theelements thereof a brief rsum of the operation vof the apparatus as awhole will now be given.

Fig. 1 shows the parts in normal position, wherein the piston 34 andplaten 36 are in their lower position of adjustment.

Nuts 18 are now adjusted to compress spring 54 to condition the pump foroperation at the desired predetermined initial pressure. actuation oflevers 60 and-6| in a clockwise direction, which in turn, through theirconnection with rods 61 and 68, actuate sliding blocks 69 of the pump toon-stroke position. By actuation'of pump 2 by motor I Il fluid frommakeup tank II will be drawn into pump 2 through pipe I2, and bedischarged therefrom through pipe I3. Fluid discharging through pipe I3now enters the central chamber I6 of valve 4.through port I4, and thenflows through port I1 and pipe I9 to the lower end of cylinder 2I ofmotor 22 causing the piston and consequently Yplate 36, to move Thiscausesv inder II'I of motor 9. Now, as the pressure in the system buildsup dueto the engagement of the work by platen 36, pistons I I8 and I2 ofmotors 9 and 1 respectively, will move in unison to the right to actuatethe sliding blocks 69 of pump 2 to leakage stroke position. If pistonsII8 and 'I2 have the same cross-sectional area' it will be seen that thepressure required to retain pump' 2f on leakage stroke position will beone-half of that required to retain it in said positionshould motor 'Ibe operating alone.

It therefore is seen that the pressure exerted upon the work may besubstantially reduced by simply actuatng valve Ii. Under some conditionsit may be desirable to operate the' pump at a higher pressure duringthe'working stroke vof piston 34, but to reduce the pressure when theplaten reaches its normal position of adjustment, and thereby decreasethe load4 on the parts during waiting periods. Under such conditionslever IIIJ of valve 6 remains in its lower positions, as shown in Fig.1, when valve 4 is adjusted, as shown in Fig. 1. However, when continuedoperation of the pump piston 8| further compresses the spring, therebycausing the pump to actuate at a still higher pressure. Such a controlis highly desirable where the materials to be compressed are of such anature that it is desirable to first maintain one pressure thereon, andto thereafter increase the pressure to a higher value and to retain thatpressure on the Work for a predetermined period of time.

When the operation has been completed, the operator simply moves lever3| to the dotted line position shown in Fig. 1, thereby causing areversal of the flow of fluid to cylinder 2l, whereupon piston 34 againmoves downwardly. Lever 94 is now moved to its lower position ofadjustment, as shown in Fig. 1, and if desired lever H may be movedupwardly, as shown in Fig. 4, so that when piston 34 reaches itslowermost position of adjustment the load imposed upon pump 2 and motorI0 will be reduced to a minimum. Y

From the foregoing descriptionI it is apparent that a simplified, aswell as highly efficient control device has been provided. The variousadjustable features associated with the device enable operation thereofthrough a wide range of pressures. The device therefore may be employedfor various uses wherein such variable pressures are desired.

While the embodiment herein shown and described is admirably adapted tofulfill the objects primarily stated, it is to be understood that it isnot intended to limit the invention thereto, since it may be embodied inother forms, all coming within the scope of the claims which follow.

What is claimed is:

1. In a fluid system, the combination of a vari` able stroke pump,control means for said pump including adjustable resilient means forplacing said pump on stroke, fluid pressure means operatively` connectedto the pressure side of said pump and operating in opposition to saidre'silient means for actuating said pump toward neutral position,additional iiuid pressure means operatively' connected to the pressureside of said pump and adapted to operate in unison with said firstmentioned fluid pressure means, a valve for connecting or disconnectingsaid second fluid pressure means from the pressure side of said pump,and power means operable upon said resilient means for changing theinitial adjustment thereof.

2. In a fluid system, the combination of a variable stroke pump, meansincluding an adjustable spring for placing said pump on stroke, a fluidmotor connected to the pressure side of said pump and operating inopposition to said spring, whereby when the pressure developed by saidpump exceeds the compression of said spring said fluid motor actuatessaid pump towards leakage stroke position, a sec'ond uid motor operableupon said spring to further compress the same, whereby said pump remainson stroke at a higher predetermined pressure, means for predeterminingthe extent of movement of said second uid motor, and means fordecreasing the pressure developed by said pump, said last mentionedmeans comprising a third fluid motor adapted to operate in unison withsaid rst mentioned uid motor. l

3. In a fluid system, the combination of a variable Ystroke pump, avalve for controlling the operation of said motor, means including an.

adjustable spring for placing said pump on stroke, uid motorvmeansacting in opposition to said spring and adapted to actuate said pump toleakage stroke position when the pressure developed by said pump exceedsthe pressure of said spring, a second fluid motor means adapted tooperate in unison with said rst mentioned motor means, thereby enablingoperation of said pump at a lower pressure, a valve for controlling theoperation of said second fluid motor means, a third fiuidmotor means,said last mentioned motor means being adapted to actuate said spring todifferent positions of adjustment, means for predetermining theadjustment of said spring by said third fluid motor means, and valvemeans for controlling the operation of said third fluid motor means.

PAUL N. OBERHOLTZER.

